1. Field of the Invention
Chemical analyses of soils provide vital information for soil classification, plant nutrition, pollution control, and other soil-related matters. It is estimated that from 20,000 to 1,000,000 soil samples are analyzed annually, with the work approximately equally divided between publicly subsidized service laboratories and commercial laboratories. Most of the cost of this service is associated with extraction and purification steps required to prepare samples for analysis. This invention avoids completely the requirement of centrifugation and/or mechanical filtration while extraction a representative sample of the exchangeable ions.
2. Description of the Prior Art
The capability for ion exchange of both soils and synthetic resins has been recognized and documented extensively for several decades [Ion Exchange, McGraw-Hill Book Company, Inc., New York, NY, 1962; A Textbook of Soil Chemical Analysis, Chemical Publishing Company, Inc., New York, NY, 1972; Methods of Soil Analysis, Part 2, Chemical and Microbial Properties, American Society of Agronomy, Inc., and Soil Science Society of America, Inc., Madison, WI 1982]. Contemporary methods of determining the exchangeable/available ions in soil or complex and colloidal matrices rests almost exclusively on extensive use of mechanical technology (centrifuge, colorimeters, and mechanical filtration devices) and the chemical law of mass action wherein a salt solution that does not contain the chemical species of interest is introduced in such an overwhelming amount that the ion of interest is brought into solution. In most instances multiple element assays are limited because of various salt interactions. Contemporary methods preclude rapid and economical determination of the relative effects of oxidation-reduction potentials on the availability of trace elements in solution.